论文标题
II型dirac节点线中的双kagome layered csv $ _8 $ sb $ _ {12} $
Type-II Dirac Nodal Lines in double-kagome-layered CsV$_8$Sb$_{12}$
论文作者
论文摘要
Lorentz-violating II Dirac Nodal Line semimetals（DNLSS），托管由两个具有相同斜率迹象的分散分支形成的带退化的曲线，代表了一种新的物质状态。从理论上进行广泛研究的同时，令人信服的II型DNLS的实验证据仍然难以捉摸。最近，基于钒的kagome材料已成为研究晶格对称性和带拓扑之间的相互作用的肥沃场所。在这项工作中，我们研究了双kagome层的CSV $ _8 $ sb $ _ {12} $的低能带结构，并将其确定为受镜面对称性保护的稀缺类型II DNL。我们已经观察到多个DNL通过角度分辨光发射光谱（ARPES）组成的II型Dirac锥或几乎在费米水平上的多个DNL。第一原则分析表明，自旋轨道耦合只会打开一个较小的间隙，从而有效地导致无间隙ARPES光谱，但产生了较大的自旋浆果曲率。这些类型的II DNL，以及我们在同一材料中观察到的低能量Van Hove Singularity和Quasi-1D乐队之间的相互作用，建议CSV $ _8 $ _8 $ SB $ _ {12} $作为探索新颖的运输属性的理想平台，用于探索诸如Hishiral Anomaly，Klein Tunnelling tunnellational tunnellational tunnaltional and fractional Halls and Fractimal and fractiment and fractum and fractiment and fractiment and fractimunt and fallaction tunnal tunnally。
Lorentz-violating type-II Dirac nodal line semimetals (DNLSs), hosting curves of band degeneracy formed by two dispersion branches with the same sign of slope, represent a novel states of matter. While being studied extensively in theory, convincing experimental evidences of type-II DNLSs remain elusive. Recently, Vanadium-based kagome materials have emerged as a fertile ground to study the interplay between lattice symmetry and band topology. In this work, we study the low-energy band structure of double-kagome-layered CsV$_8$Sb$_{12}$ and identify it as a scarce type-II DNLS protected by mirror symmetry. We have observed multiple DNLs consisting of type-II Dirac cones close to or almost at the Fermi level via angle-resolved photoemission spectroscopy (ARPES). First-principle analyses show that spin-orbit coupling only opens a small gap, resulting effectively gapless ARPES spectra, yet generating large spin Berry curvature. These type-II DNLs, together with the interaction between a low-energy van Hove singularity and quasi-1D band as we observed in the same material, suggest CsV$_8$Sb$_{12}$ as an ideal platform for exploring novel transport properties such as chiral anomaly, the Klein tunneling and fractional quantum Hall effect.
